Cross-linking reaction during melt kneading produces resinous electrophotographic toner

Abstract

A process for producing an electrophotographic toner composition comprising melt-kneading (a) a cross-linkable functional group-containing resin and (b) a colorant, with (c) a polyfunctional resin capable of reacting with the cross-linkable functional group-containing resin (a) or a low molecular weight cross-linking agent capable of cross-linking the cross-linkable functional group-containing resin (a), the amount of the polyfunctional resin or the low molecular weight cross-linking agent (c) being such that the amount of the functional groups present in the polyfunctional resin or the low molecular weight cross-linking agent (c) being equivalent to or less than equivalent to the amount of the functional group present in the cross-linkable functional group-containing resin (a); cross-linking by heating and generating a shearing force during melt-kneading to produce a slightly cross-linked colored resin such that the adhesion properties and the grindability of the slightly cross-linked colored resin are not deteriorated, and pulverizing the slightly cross-linked colored resin to produce the electrophotographic toner composition.

What is claimed is: 
     
       1. A process for producing an electrophotographic toner composition comprising melt-kneading (a) a cross-linkable functional group-containing resin containing functional groups in a proportion of about 5 to about 50 mol% and (b) a colorant, with (c) a polyfunctional resin capable of reacting with the cross-linkable functional group-containing resin (a) or a low molecular weight cross-linking agent capable of cross-linking the cross-linkable functional group-containing resin (a), the amount of the polyfunctional resin or the low molecular weight cross-linking agent (c) being such that the amount of the functional groups present in the polyfunctional resin or the low molecular weight cross-linking agent (c) being equivalent to or less than equivalent to the amount of the functional groups present in the cross-linkable functional group-containing resin (a); cross-linking by heating and generating a shearing force during melt-kneading to produce a slightly cross-linked colored resin such that the adhesion properties and the grind-ability of the slightly cross-linked colored resin are not deteriorated, and pulverizing the slightly cross-linked colored resin to produce the electrophotographic toner composition. 
     
     
       2. The process of claim 1, wherein said cross-linkable functional group-containing resin (a) is an acrylic resin or a polyester resin. 
     
     
       3. The process of claim 2, wherein said acrylic resin is an acrylic copolymer comprising the radical polymerization product of (A) an acrylate or a methacrylate, (B) a vinyl monomer reactive on heating and (C) a modified vinyl monomer copolymerizable with said acrylate or methacrylate (A) and said vinyl monomer (B). 
     
     
       4. The process of claim 2, wherein said polyester resin is the condensation polymerization product of (D) a divalent alcohol, (E) a dicarboxylic acid and (F) a polyhydric alcohol having 3 or more hydroxy groups or a polycarboxylic acid having 3 or more carboxyl groups. 
     
     
       5. The process of claim 1, wherein said cross-linkable functional group-containing resin (a) has a molecular weight ranging from about 1,500 to about 5,000. 
     
     
       6. The process of claim 1, wherein said cross-linkable functional group-containing resin (a) has a glass transition temperature of between 40° C. and 60° C. 
     
     
       7. The process of claim 1, wherein said polyfunctional resin (c) capable of reacting with said cross-linkable functional group-containing resin (a) is an epoxy resin, a polyamide resin, a polysulfide resin, a urea-formaldehyde resin, a phenol-formaldehyde resin, a melamine resin, an aniline resin, a toluenesulfonamide resin, an isocyanate resin, an alkyd resin, a furfural resin or a silicone resin. 
     
     
       8. The process of claim 1, wherein said low molecular weight cross-linking agent (c) is ethylenediamine, diethylenediamine, triethylenetetramine, diethylaminopropylamine, m-phenylenediamine, naphthylenediamine, succinic acid or phthalic acid. 
     
     
       9. The process of claim 1, wherein the amount of the functional groups present in said cross-linkable functional group-containing resin (a) to the functional groups present in said polyfunctional resin or said low molecular weight cross-linking agent (c) ranges from 0.5:1 to 0.1:1 on molar basis. 
     
     
       10. The process of claim 1, wherein said colorant is a pigment or a dye. 
     
     
       11. The process of claim 1, wherein said melt-kneading is at a temperature of at least about 50° C. 
     
     
       12. The process of claim 1, wherein said pulverizing is to a particle size of about 30 microns or less. 
     
     
       13. The process of claim 1 wherein the only cross-linking step to produce said toner composition is during said melt-kneading. 
     
     
       14. The process of claim 1 wherein said cross-linkable functional-group containing resin contains functional groups in a proportion of 15 to 30 mol%. 
     
     
       15. The process of claim 1 wherein said cross-linking is carried out to such an extent that the glass transition point of the resin is not substantially increased. 
     
     
       16. The process of claim 1 wherein said cross-linkable functional-group containing resin (a) is an acrylic resin or a polyester resin having a molecular weight ranging from about 1500 to 5000, wherein said polyfunctional resin (c) is an epoxy resin, a polyamide resin, a polysulfide resin, a urea-formaldehyde resin, a phenol-formaldehyde resin, a melamine resin, an aniline resin, a toluenesulfonamide resin, an isocyanate resin, an alkyd resin, a furfural resin or a silicone resin, said low molecular weight cross-linking agent (c) is ethylenediamine, diethylenediamine, triethylenetetramine, diethylaminopropylamine, m-phenylenediamine, naphthylenediamine, succinic acid or phthalic acid, and wherein the amount of the functional groups present in said cross-linkable functional group-containing resin (a) to the functional groups present in said polyfunctional resin or said low molecular cross-linking agent (c) ranges from 0.5:1 to 1.0:1 on a molar basis, wherein said colorant is a pigment or a dye, wherein said melt-kneading is at a temperature of at least about 50° C. and wherein said pulverizing is to a particle size of about 30 microns or less. 
     
     
       17. The process of claim 16 wherein said colorant is carbon black. 
     
     
       18. The process of claim 1 wherein said toner composition consists essentially of the reaction products to components (a), (c) and said colorant. 
     
     
       19. The process of claim 16 wherein component (a) is an acrylic resin and component (c) is an alkyl phenol modified xylene resin and said colorant is carbon black.